* {
	margin: 0；
	padding:0;
}


.wrapper {
	/*border: 10px solid green;*/
	width: 200px;
	height: 200px;
	background-color: red;
	padding: 10px 20px 30px 40px;  /*上 右 下 左   上 左右 下   上下 左右*/
}

.content {
	position: absolute;
	left: 100;
	top: 200;
	width: 100px;
	height: 100px;
	background-color: black;
}

.demo {
	position: relative;
	width: 100px;
	height: 100px;
	background-color:  red;
	opacity: 0.5;
}

.box {
	width: 200px;
	height: 200px;
	background:  green;
}


.demo1 {
	margin-left: 200px;
	width: 200px;
	height: 200px;
	background-color: red;
}


.demo2 {
	position: absolute;
	left: 100px;
	width: 100px;
	height: 100px;
	background-color: green;
}


.demo3 {
	position: relative;
	left: 50px;
	width: 50px;
	height: 50px;
	background-color: orange;
}

.center {
	position: fixed;
	left: 50%;
	top: 50%;
	width: 300px;
	height: 200px;
	background-color: red;
	margin-left: -150px;
	margin-top: -100px;


	line-height: 200px;
	font-size: 100px;
	text-align: center;;
	color: white;
}







